|Creature (Other Planes)|Page|Other Appearances|Variants|Description|
|---|---|---|---|---|
|Aerial Servant|39|Rules Cyclopedia (1991)|||
|Basilisk|39|D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991)||Describes additional abilities/penalties applicable to native plane of existence.|
|Cockatrice|39|D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991)||Describes additional abilities/penalties applicable to native plane of existence.|
|Djinni, Lesser|39|D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991)||Describes additional abilities/penalties applicable to native plane of existence.|
|Djinni, Greater|39|Rules Cyclopedia (1991)|||
|Efreeti, Lesser|39|D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991)||Describes additional abilities/penalties applicable to native plane of existence.|
|Efreeti, Greater|39-40|Rules Cyclopedia (1991)|||
|Elemental|40|D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991)||Describes additional statistics and abilities/penalties applicable to native plane of existence.|
|Gorgon|40|D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991)||Describes additional abilities/penalties applicable to native plane of existence.|
|Helion|40|Rules Cyclopedia (1991)|||
|Horde|41|Rules Cyclopedia (1991)|||
|Hydrax|41|Rules Cyclopedia (1991)|||
|Invisible Stalker|41|D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991)||Describes additional abilities/penalties applicable to native plane of existence.|
|Kryst|42|Rules Cyclopedia (1991)|||
|Medusa|42|D&D Basic Rules (1981), D&D Basic Rules (1983), Rules Cyclopedia (1991)||Describes additional abilities/penalties applicable to native plane of existence.|
|Plasm|42|Rules Cyclopedia (1991)|Normal and giant||
|Salamander|42|D&D Expert Rules (1981), D&D Expert Rules (1983), Rules Cyclopedia (1991)||Describes additional abilities/penalties applicable to native plane of existence.|
|Undine|42|Rules Cyclopedia (1991)|||

Question: how many creatures are included before page 42?
Answer: 13